This research aims to produce teaching material products. Where the teaching materials developed in this research are LKPD (Student Worksheets) based on HOTS (High Order Thinking Skill). The LKPD teachers in this research used the CTL (Contextual Teaching and Learning) learning strategy. This type of research is Research and Development (R & D). The research and development procedure in this research is to use the Dick and Carey Model. The development of this research is the development of HOTS-based LKPD to improve critical thinking and mathematical reasoning skills in class VI elementary school students using the CTL learning model at SDN O l Pematang Jering, Sei Suka District, Batu Bara Regency.
The results of this research are that there is an increase in students' critical thinking and mathematical reasoning abilities. This can be seen from the average increase in students' critical thinking skills from trial I to trial II, namely that more than 70% of students have very good critical thinking skills and the rest are able to think critically well. The increase in mathematical reasoning abilities can be seen from the average learning outcomes of students in trial I which was 79.28 and trial II was 89.28.
Based on data obtained from interviews, expert opinions, test results, questionnaires, learning implementation and student responses, the HOTS-based LKPD developed is in the- Practical and Effective-category. Practically, it can be seen from experts and practitioners who state that the HOTS-based LKPD developed can be used with several revisions, the LKPD is easy to use for both teachers and students, and the implementation of CTL learning is said to be successful in the Good category. Effective criteria can be seen from the achievement of individual and classical learning objectives and students' attitudes towards the HOTS-based LKPD developed showing positive results. The HOTS­based LKPD developed is· suitable and can be used as teaching material, in the lesson material for building tubes in class VI elementary schools.